kasan, arm64: print report from tag fault handler

Add error reporting for hardware tag-based KASAN. When CONFIG_KASAN_HW_TAGS is enabled, print KASAN report from the arm64 tag fault handler. SAS bits aren't set in ESR for all faults reported in EL1, so it's impossible to find out the size of the access the caused the fault. Adapt KASAN reporting code to handle this case. Link: https://lkml.kernel.org/r/b559c82b6a969afedf53b4694b475f0234067a1a.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <[email protected]> Co-developed-by: Vincenzo Frascino <[email protected]> Signed-off-by: Vincenzo Frascino <[email protected]> Reviewed-by: Catalin Marinas <[email protected]> Reviewed-by: Alexander Potapenko <[email protected]> Tested-by: Vincenzo Frascino <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Branislav Rankov <[email protected]> Cc: Dmitry Vyukov <[email protected]> Cc: Evgenii Stepanov <[email protected]> Cc: Kevin Brodsky <[email protected]> Cc: Marco Elver <[email protected]> Cc: Vasily Gorbik <[email protected]> Cc: Will Deacon <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
berg · Dec 22, 2020 · 4291e9e · 4291e9e
1 parent 2e903b9
commit 4291e9e
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Showing 2 changed files with 22 additions and 3 deletions.
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
@@ -14,6 +14,7 @@
 #include <linux/mm.h>
 #include <linux/hardirq.h>
 #include <linux/init.h>
+#include <linux/kasan.h>
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
 #include <linux/page-flags.h>
@@ -297,10 +298,23 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
 	do_exit(SIGKILL);
 }
 
+#ifdef CONFIG_KASAN_HW_TAGS
 static void report_tag_fault(unsigned long addr, unsigned int esr,
 			     struct pt_regs *regs)
 {
+	bool is_write  = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
+
+	/*
+	 * SAS bits aren't set for all faults reported in EL1, so we can't
+	 * find out access size.
+	 */
+	kasan_report(addr, 0, is_write, regs->pc);
 }
+#else
+/* Tag faults aren't enabled without CONFIG_KASAN_HW_TAGS. */
+static inline void report_tag_fault(unsigned long addr, unsigned int esr,
+				    struct pt_regs *regs) { }
+#endif
 
 static void do_tag_recovery(unsigned long addr, unsigned int esr,
 			   struct pt_regs *regs)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
@@ -62,9 +62,14 @@ static void print_error_description(struct kasan_access_info *info)
 {
 	pr_err("BUG: KASAN: %s in %pS\n",
 		get_bug_type(info), (void *)info->ip);
-	pr_err("%s of size %zu at addr %px by task %s/%d\n",
-		info->is_write ? "Write" : "Read", info->access_size,
-		info->access_addr, current->comm, task_pid_nr(current));
+	if (info->access_size)
+		pr_err("%s of size %zu at addr %px by task %s/%d\n",
+			info->is_write ? "Write" : "Read", info->access_size,
+			info->access_addr, current->comm, task_pid_nr(current));
+	else
+		pr_err("%s at addr %px by task %s/%d\n",
+			info->is_write ? "Write" : "Read",
+			info->access_addr, current->comm, task_pid_nr(current));
 }
 
 static DEFINE_SPINLOCK(report_lock);